The present invention relates to a disk player and, more particularly, to a front loading type disk player equipped with a carrying transport mechanism that automatically conveys a disk type recording medium between a recording/reproducing position inside the housing of the player and a loading/unloading position where it is projected from the housing.
A front loading disk player is known in which an audio disk, such as an analog recording medium having a sound groove cut into its surface or a digital audio disk having digital PCM signals recorded on its surface, is held on a carriage that can be slid to project from the front of a player housing or which can be entirely accommodated within the housing. In such a front loading player, the space on the top of the player can be utilized, for example, to support another audio system device.
Such a front loading disk player is basically composed of the following components: a player housing; a playing mechanism accommodated in the housing and which is composed of such parts as a turnable for supporting and rotating the recording medium, a mechanism that automatically starts, drives and stops the disk type recording medium on the turntable, and a pickup for effecting information recording or reproduction from the recording medium; a carriage that holds, guides and transports the disk to the playing position; and a transport mechanism for moving the carriage to a loading/unloading position in which the carriage projects from the housing or to a recording and reproducing position inside the housing.
The transport mechanism employed in a typical conventional front loading disk player, however, does not protrude completely from the housing, but can slide only partly to the outside of the latter. The user, therefore, has to pull the carriage manually to the position necessary for loading or unloading the disk, and once the disk has been loaded into the carriage, the carriage must be pushed into a position where reading and reproducing can be started. In other words, the loading mechanism in the conventional front loading disk player is only semi-automatic.
A need therefore exists to permit the carriage to project and to be accommodated completely in a fully automatic way, thereby simplifying to a maximum extent the procedures of loading and playing a disk type recording medium.
It is rather easy to design various types of fully automatic loading mechanism if several independent drive sources are available, a relatively large number of control switches are used, and if the depth of the player housing is great enough to provide a large space. On the other hand, it is difficult to design a fully automatic loading mechanism while satisfying the requirement for a small overall size using a single drive source (i.e., one motor) and a player housing with a minimum depth.
The assignee of the present invention has though successfully developed a loading mechanism that basically satisfied such challenging design conditions. The heart of this such loading mechanism is an operation control member installed on the rising portion of a chassis (this portion is hereinafter referred to as a subchassis) and which is designed so that it can be moved toward or away from the user without exceeding the depth of the player housing, even if it is moved to the extreme end in either direction. By moving this control member toward and away from the user over a restricted range, the carriage is allowed to projected to an unloading position, be accommodated in the housing, and be lowered in association with the playing mechanism with the disk type recording medium being subsequently loaded and clamped on the turntable at a recording or reproducing position. The sequence of these operations is performed in a controlled manner, with the motor (drive source) being simply used to impart a driving force that causes the operation control member to be moved either toward or away from the user. In short, the operation control member is the key factor to the operation of the new loading mechanism. The drive force imparted to this operation control member is converted to a force that causes movement in the forward or backward direction with respect to the chassis. With this movement used as a secondary drive source, the carriage is subjected to an accelerated movement either toward the user (i.e., in such a way that it projects to the unloading position), or away from the user (i.e., in such a way that it is accommodated in the housing). The carriage is then lowered in association with the playing mechanism as its position is properly controlled, and, finally, the disk type recording medium is loaded and clamped on the turntable at the recording or reproducing position. While the operation control member performs these several functions, the drive force is distributed in such a way that the individual components and mechanisms are operated in a controlled, timed and smooth manner.
The system described above is very effective for the purpose of reducing the size and weight of the operating mechanism, the number of parts, and the total costs.
However, this loading mechanism, in which the drive force imparted to the operation control member is transmitted via a number of components to effect various kinds of operations, suffers from the inevitable disadvantage that the number of tolerances (amounts of play) between adjacent components is increased. The tolerances stack so as to reduce the operational precision and cause a delay (i.e., backlash) in the movement of the overall mechanism. In particular, if the movement is amplified by some accelerating device, such play or backlash is also amplified, causing a marked drop in operational precision. This phenomenon is not a problem in cases where no high operational precision is required, but presents a serious problem in other situations, such as where it is necessary to lower the carriage in the loading direction with its position being precisely controlled in order to accurately clamp the recording medium at the recording or reproducing position. This is particularly true for the case where the carriage is to be moved away from the user (i.e., in the direction in which it is accommodated in the housing). If a large delay or excessive play occurs in the movement of the carriage in this direction, the position at which the carriage is lowered will be offset and the position at which the disk is switched from the recording to reproducing position or vice versa inaccurately determined, causing a serious problem, namely, inability to switch between the recording and reproducing positions of the disk.